首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   28544篇
  免费   1378篇
  国内免费   96篇
耳鼻咽喉   410篇
儿科学   1744篇
妇产科学   662篇
基础医学   3043篇
口腔科学   596篇
临床医学   1659篇
内科学   6173篇
皮肤病学   798篇
神经病学   1690篇
特种医学   1008篇
外科学   3810篇
综合类   819篇
一般理论   19篇
预防医学   1332篇
眼科学   1437篇
药学   2500篇
中国医学   200篇
肿瘤学   2118篇
  2023年   201篇
  2022年   481篇
  2021年   991篇
  2020年   487篇
  2019年   654篇
  2018年   839篇
  2017年   584篇
  2016年   721篇
  2015年   699篇
  2014年   1066篇
  2013年   1326篇
  2012年   1863篇
  2011年   2096篇
  2010年   1132篇
  2009年   963篇
  2008年   1432篇
  2007年   1475篇
  2006年   1473篇
  2005年   1283篇
  2004年   1174篇
  2003年   962篇
  2002年   889篇
  2001年   712篇
  2000年   720篇
  1999年   574篇
  1998年   257篇
  1997年   194篇
  1996年   167篇
  1995年   160篇
  1994年   126篇
  1993年   111篇
  1992年   375篇
  1991年   376篇
  1990年   347篇
  1989年   331篇
  1988年   288篇
  1987年   254篇
  1986年   236篇
  1985年   235篇
  1984年   175篇
  1983年   135篇
  1981年   99篇
  1979年   160篇
  1978年   98篇
  1977年   81篇
  1975年   83篇
  1974年   100篇
  1973年   92篇
  1972年   119篇
  1970年   78篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.

Background

Treatment of esophageal adenocarcinoma often involves surgical resection. Newer technologies in interventional endoscopy have led to a substantial paradigm shift in the management of early-stage neoplasia in Barrett’s esophagus comprising high-grade dysplasia (HGD), intramucosal carcinoma, and, in some cases, submucosal carcinoma. However, there has been no consensus regarding the indications for esophageal preservation in these cases. In this work, consensus guidelines were established for the management of early-stage esophageal neoplasia considering clinically relevant aspects (age, comorbidities, and social environment) in each scenario.

Methods

Seventeen experts were invited to participate based on their background and clinical expertise at high-volume centers. A questionnaire was created that included four clinical scenarios covering a wide range of situations within HGD and/or early esophageal neoplasia, particularly where controversies are likely to exist. Each of the clinical scenarios was open to discussion subdivided by patient age (20, 50, and 80 s). For each clinical scenario an expert was chosen to defend that position. Each defense triggered a subsequent discussion during a consensus meeting. Conclusions of that discussion together with an accompanying literature analysis allowed experts to confirm or change their original choices and served as the basis for the recommendations stated in this article.

Results

There was 100 % consensus supporting esophageal preservation in patients with HGD, independent of patient age or Barrett’s length. In patients with T1a adenocarcinoma, consensus for preservation was not reached (65 %) for young and middle-aged individuals but was supported for elderly patients (100 %). For T1b adenocarcinoma, consensus was reached for surgical resection (90 %), leaving organ preservation for patients with very low risk of nodal invasion or poor surgical candidates.

Conclusion

Advances in endoscopic imaging and therapy allow for organ preservation in most settings of early-stage neoplasia of the esophagus, provided that the patient understands the implications of this decision.  相似文献   
992.
993.

Background

Currently, the long-term advantages of having a pancreas transplantation (PT) are debated, particularly in patients receiving pancreas after kidney (PAK) allografts. The United Network for Organ Sharing (UNOS) requires that a transplant center perform a minimum number of PT per year to remain an active PT center. The long-term outcomes and challenges of PAK in small pancreas transplant centers are not well studied.

Methods

In this retrospective analysis, we report short- and long-term outcomes in a small center performing 2–9 PT annually.

Results

Forty-eight PT (25 simultaneous pancreas and kidney transplantation [SPK], 23 PAK) were performed in our center. Donor and recipient demographics were similar in both groups. All suitable local donors were used for SPK. All organs for PAK transplantation were imported from other UNOS regions. Mean follow-up was 61 ± 46 and 74 ± 46 months for SPK and PAK, respectively. Patient and graft survival rates were similar in SPK and PAK groups and better than the reported national average. Four patients (11%) died (1 due to trauma, 1 brain lymphoma, 1 ruptured aneurysm; and 1 unknown cause). Two patients (4%; 1 SPK, 1 PAK) lost their grafts because of thrombosis on postoperative days 3 and 5 in 2002. No graft thrombosis occurred since 2002. Seven patients (15%) required reoperation (4 for bleeding, 2 anastomotic leaks, 1 small bowel perforation). Two patients (4%) developed post-transplantation lymphoproliferative disease. Five patients (11%) experienced cytomegalovirus antigenemia which responded well to antiviral therapy.

Conclusions

Compared with outcomes for diabetic patients on dialysis, current SPK and PAK short- and long-term results are favorable even in a small PT center. Therefore, unless there is a contraindication, PT should be offered to all type 1 diabetic patients with end-stage renal disease at the time of kidney transplantation or afterward.  相似文献   
994.

Introduction

The optimal treatment of high energy tibial fractures remains controversial and a challenging orthopaedic problem. The role of external fixators for all these tibial fractures has been shown to be crucial.

Methods

A five-year consecutive series was reviewed retrospectively, identifying two treatment groups: Ilizarov and Taylor Spatial Frame (TSF; Smith & Nephew, Memphis, TN, US). Fracture healing time was the primary outcome measure.

Results

A total of 112 patients (85 Ilizarov, 37 TSF) were identified for the review with a mean age of 45 years. This was higher in women (57 years) than in men (41 years). There was no significant difference between frame types (p=0.83). The median healing time was 163 days in both groups. There was no significant difference in healing time between smokers and non-smokers (180 vs 165 days respectively, p=0.07), open or closed fractures (p=0.13) or age and healing time (Spearman''s r=0.12, p=0.18). There was no incidence of non-union or re-fracture following frame removal in either group.

Conclusions

Despite the assumption of the rigid construct of the TSF, the median time to union was similar to that of the Ilizarov frame and the TSF therefore can play a significant role in complex tibial fractures.  相似文献   
995.
The Sturge Weber syndrome is characterized by developmental delay, seizures in infancy, unilateral cutaneous lesions with ipsilateral leptomeningeal enhancement. We report an unusual presentation of Sturge Weber syndrome with bilateral port wine nevus on the trunk and face along with bilateral cortical involvement in a developmentally normal child with progressive megalencephaly.  相似文献   
996.
Symptomatic neurosyphilis (NS) can have varied syndromic presentations: Meningitis, meningovascular and parenchymatous involvement. Non-tabetic syphilis affecting the spinal cord is rare and only sporadic case reports have been published. The variant of meningomyelitis known as Erb''s paraplegia refers to patients of spinal syphilis with very slow progression over many years and predominantly motor signs. Primary optic atrophy occurs twice as frequently in tabes dorsalis as in other types of NS. We describe here a case of a 32-year-old truck driver who presented with Erb''s paraplegia with primary optic atrophy. This clinical overlap in NS is extremely rare and to our knowledge is the first case report of its type.  相似文献   
997.
998.
Currently, no blood biomarker that specifically indicates injury to the proximal tubule of the kidney has been identified. Kidney injury molecule-1 (KIM-1) is highly upregulated in proximal tubular cells following kidney injury. The ectodomain of KIM-1 is shed into the lumen, and serves as a urinary biomarker of kidney injury. We report that shed KIM-1 also serves as a blood biomarker of kidney injury. Sensitive assays to measure plasma and serum KIM-1 in mice, rats, and humans were developed and validated in the current study. Plasma KIM-1 levels increased with increasing periods of ischemia (10, 20, or 30 minutes) in mice, as early as 3 hours after reperfusion; after unilateral ureteral obstruction (day 7) in mice; and after gentamicin treatment (50 or 200 mg/kg for 10 days) in rats. In humans, plasma KIM-1 levels were higher in patients with AKI than in healthy controls or post-cardiac surgery patients without AKI (area under the curve, 0.96). In patients undergoing cardiopulmonary bypass, plasma KIM-1 levels increased within 2 days after surgery only in patients who developed AKI (P<0.01). Blood KIM-1 levels were also elevated in patients with CKD of varous etiologies. In a cohort of patients with type 1 diabetes and proteinuria, serum KIM-1 level at baseline strongly predicted rate of eGFR loss and risk of ESRD during 5–15 years of follow-up, after adjustment for baseline urinary albumin-to-creatinine ratio, eGFR, and Hb1Ac. These results identify KIM-1 as a blood biomarker that specifically reflects acute and chronic kidney injury.  相似文献   
999.
ObjectiveTo test the hypothesis that sexual dysfunction in elderly men with benign prostatic hyperplasia leads to prostatic inflammation, diagnosed by prostatic fluid interleukin-8 (IL-8), which lowers the positive predictive value of prostate-specific antigen (PSA).MethodsOverall, 160 men with lower urinary tract symptoms between 50 and 75 years of age with an elevated PSA level of more than 4 ng/ml with normal digital rectal examination and 50 age-matched controls with normal PSA level were prospectively evaluated for prostatic fluid IL-8 levels. Erectile dysfunction was measured by self-administered questionnaire of the Sexual Health Inventory for Men. Total and free serum PSA levels and IL-8 in prostatic fluid were measured 6 to 8 weeks after a course of 400 mg of ofloxacin and 20 mg of piroxicam given daily for 2 weeks. Transrectal ultrasonography–guided biopsy was done only when PSA level did not decrease less than 4 ng/ml.ResultsMean ages of patients and controls were 63.18 (standard deviation [SD]±7.10) and 60.18 (SD+6.02) years, respectively. Mean concentration of IL-8 in prostatic fluid of the patients was significantly higher, i.e., 6678 pg/ml (SD±1985.7) than in control, i.e., 1543 pg/ml (SD±375.7) (P<0.001). Following anti-inflammatory treatment, there was a significant decrease in the mean level of IL-8 from baseline to 5622 pg/ml (SD±1870.66) (P<0.001). Corresponding to this, a significant decrease was noted in total PSA levels to less than 4 ng/ml in 105 (65.62%) patients. Men with the highest levels of IL-8 had a greater degree of erectile dysfunction.ConclusionMen with symptomatic benign prostatic hyperplasia and erectile dysfunction had significant inflammation of the prostate to cause spurious rise in PSA level resulting in an unnecessary biopsy.  相似文献   
1000.
ObjectivesInfection by high-risk human papillomavirus (HR-HPV) plays an important role in the pathogenesis of penile cancer in approximately 50% of the patients. The gold standard for human papillomavirus (HPV) detection is the polymerase chain reaction (PCR) assay. However, technical requirements and associated costs preclude the worldwide use of PCR assays on a routine basis. Herein, we evaluated the predictive abilities of tumor morphology, immunohistochemistry for p16INK4a expression, and in situ hybridization (ISH) for HR-HPV detection in defining HPV status, as established by PCR.Materials and methodsTissue samples from 48 patients with HPV-positive penile squamous cell carcinoma (SCC) were included in 4 tissue microarrays (TMA).ResultsSensitivities and specificities were as follows: tumor morphology, 70% and 68%; p16INK4a immunohistochemistry, 65% and 90%; HR-HPV ISH, 47% and 100%. Regarding combinations of the predictors, the best performance was seen when HR-HPV ISH and p16INK4a immunohistochemistry were combined, regardless of the tumor morphology: sensitivity, 88%; specificity, 64%; area under the receiver-operating characteristic (AUC) curve, 0.83. Combinations of tumor morphology with p16INK4a immunohistochemistry or with HR-HPV ISH performed similarly well.ConclusionsIn penile SCC, both p16INK4a immunohistochemistry and ISH for HR-HPV increase the predictive ability of routine morphology in defining HPV status. These tests can be interpreted differentially, depending on the necessity of a higher sensitivity or a higher specificity. For research/screening studies, we recommend combining tumor morphology, p16INK4a immunohistochemistry, and HR-HPV ISH. To increase sensitivity, positivity in any of these predictors should be considered as indicative of HPV infection. For routine diagnosis of clinical cases, criteria should be more stringent, and, to achieve the highest specificity in classifying a case as HPV-related, all predictors should be consistently positive. The data generated in the present study could be used in algorithms for defining HPV status in penile carcinomas.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号